Capability Extensions for Multimedia Broadcast Multicast Services

ABSTRACT

A base station of a mobile communication network supports continuity of a Multimedia Broadcast Multicast Service, MBMS, for a terminal. The base station receives, from the terminal, an information element informing the base station of a combination of bands, which the terminal supports for carrier aggregation. The terminal supports MBMS reception on any carrier configurable as a serving cell for the terminal according to the information element. The base station derives, from the received information element, MBMS reception capabilities of the terminal. The base station determines a number of carriers, which are configurable by the base station as serving cell of the terminal, such that the terminal is enabled to receive at least one MBMS.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/028,882, which was filed on Jul. 6, 2018, which is acontinuation of U.S. patent application Ser. No. 15/226,335, which wasfiled on Aug. 2, 2016, now U.S. Pat. No. 10,070,413 issued on Sep. 4,2018, which is a continuation of U.S. patent application Ser. No.13/587,491, which was filed on Aug. 16, 2012, now U.S. Pat. No.9,439,171 issued on Sep. 6, 2016, and claims the benefit of U.S.Provisional Patent Application 61/524,107 filed on Aug. 16, 2011, thedisclosures of each of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present invention relates to methods in a mobile communicationnetwork, in a base station of a mobile communication network and in aterminal. The invention further relates to corresponding devices forimplementing the nodes. In particular, the invention relates tosupporting MBMS service continuity.

BACKGROUND

The Multimedia Broadcast Multicast Service (MBMS) relies on apoint-to-multipoint interface specification for existing and upcomingcellular networks. MBMS specifications are designed to provide efficientdelivery of broadcast and multicast services, both within cells of oneor more radio access networks as well as within the core network of amobile communication network. For broadcast transmission across multiplecells, MBMS specifications generally define transmissions viasingle-frequency network configurations. Applications of MBMS includemobile TV, radio broadcasting, file delivery and emergency alerts.

The Multimedia Broadcast Multicast Service (MBMS) feature for EvolvedUniversal Mobile Telecommunications System Terrestrial Radio AccessNetwork, E-UTRAN, was specified in 3GPP Rel-9 (Third GenerationPartnership Project Release 9). The scope of the 3GPP Rel-9 basicallyfocused on deployments of MBMS considering only one carrier. In areaswhere MBMS is provided, MBMS/Unicast-mixed cells are deployed. AMBMS/Unicast mixed cell is a cell that supports MBMS and unicasttransmissions on the same carrier.

For currently ongoing 3GPP work on Rel-11 (Release 11) according theWork Item Description capture in RP-110452 (TSG-RAN Meeting 51, Fukuoka,Japan, September 2011), entitled “Service continuity improvements andlocation information for MBMS for LTE”, solutions shall be developedsuch that the network may provide MBMS service continuity to the UE inmulti-frequency deployments. MBMS status reports (also referred to asMBMS interest indication) have been introduced by 3GPP to enable thenetwork to perform appropriate decisions for configuring UEs inconnected mode.

According to the above cited 3GPP Work Item Description RP-110452,Mobility procedures do not account for MBMS reception in Release-9 andRelease-10. Release-10 makes provision for deployments involving morethan one carrier and for the network could take into account a UE'scapability to operate in a specific frequency band or bands and/or tooperate on one or several carriers. Making the network aware of theservices that the UE is receiving or is interested to receive via MBMScould facilitate proper action by the network e.g., handover to a targetcell or reconfiguration of Scell(s), to facilitate service continuity ofunicast services and desired MBMS services. A UE in Idle Mode should beable to select/reselect cells in order to receive the desired service.

It is an object to obviate to obviate at least some of the abovedisadvantages and provide an improved network, base station and terminalfor telecommunications. A further object is to provide concepts whichsupport an improved MBMS service continuity. A further object is toprovide a scheme which provides improved flexibility in configuring oneor more serving cell(s) while MBMS service continuity for theterminal/UE is supported.

SUMMARY

According to one embodiment, a method in a base station of a mobilecommunication network for supporting continuity of a MultimediaBroadcast Multicast Service, MBMS, for a terminal is provided. Themethod comprises: the base station receives, from the terminal, aninformation element informing the base station of a combination ofbands, which the terminal supports for carrier aggregation, wherein theterminal supports MBMS reception on any carrier configurable as aserving cell for the terminal according to the information element; thebase station derives, from the received information element, MBMSreception capabilities of the terminal; and the base station determinesa number of carriers, which are configurable by the base station asserving cell of the terminal, such that the terminal is enabled toreceive at least one MBMS.

According to one embodiment, a method in a terminal for supportingcontinuity of a Multimedia Broadcast Multicast Service, MBMS, for theterminal is provided. The terminal sends, to a base station, aninformation element informing the base station of a combination ofbands, which the terminal supports for carrier aggregation; wherein theterminal supporting MBMS reception for any carrier configurable as aserving cell for the terminal according to the information element.

According to one embodiment, a base station for a mobile communicationnetwork and for supporting continuity of a Multimedia BroadcastMulticast Service, MBMS, for a terminal is provided. The base stationcomprises a receiver for receiving, from the terminal, an informationelement informing the base station of a combination of bands, which theterminal supports for carrier aggregation, wherein the terminal supportsMBMS reception on any carrier configurable as a serving cell for theterminal according to the information element. The bases station furthercomprises a controller for deriving, from the received informationelement, MBMS reception capabilities of the terminal, and fordetermining a number of carriers, which are configurable by the basestation as serving cell of the terminal, such that the terminal isenabled to receive at least one MBMS.

According to one embodiment, a terminal for a wireless communicationnetwork and for supporting continuity of a Multimedia BroadcastMulticast Service, MBMS, for the terminal is provided. The terminalcomprises a transmitter for sending, to a base station, an informationelement informing the base station of a combination of bands, which theterminal supports for carrier aggregation, wherein the terminal supportsMBMS reception for any carrier configurable as a serving cell for theterminal according to the information element.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically illustrates a wireless network environment in whichconcepts according to an embodiment may be applied.

FIG. 2 schematically illustrates a terminal in which concepts accordingto an embodiment may be applied.

FIG. 3 schematically illustrates a base station in which conceptsaccording to an embodiment may be applied.

FIG. 4 depicts examples of supported band combinations.

FIG. 5 shows an example of a spectrum divided into carriers and bands,wherein MBMS is provided on one carrier.

FIG. 6 schematically illustrates a flowchart of a method in a wirelessnetwork according to one embodiment.

FIG. 7 schematically illustrates a flowchart of a method in a basestation according to one embodiment.

FIG. 8 schematically illustrates a flowchart of a method in a terminalaccording to one embodiment.

FIG. 9 schematically illustrates a base station according to oneembodiment.

FIG. 10 schematically illustrates a terminal according to oneembodiment.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and notlimitation, specific details are set forth such as particulararchitectures, interfaces, techniques, etc. in order to provide athorough understanding of the present invention. However, it will beapparent to those skilled in the art that the present invention may bepracticed in other embodiments that depart from these specific details.That is, those skilled in the art will be able to devise variousarrangements which, although not explicitly described or shown herein,embody the principles of the invention and are included within itsspirit and scope. In some instances, detailed descriptions of well-knowndevices, circuits, and methods are omitted so as not to obscure thedescription of the present invention with unnecessary detail. Allstatements herein reciting principles, aspects, and embodiments, as wellas specific examples thereof, are intended to encompass both structuraland functional equivalents thereof. Additionally, it is intended thatsuch equivalents include both currently known equivalents as well asequivalents developed in the future, i.e., any elements developed thatperform the same function, regardless of structure.

FIG. 1 schematically illustrates a wireless network environment 101 inwhich concepts according to an embodiment may be applied. The wirelessnetwork environment 101 comprises infrastructure of a wireless network,represented by base stations 102, 103 and 104 and by terminals 105, 106,107. In accordance with the addressed LTE scenario, the base stationsmay also be referred to as eNodeBs and the terminals may also bereferred to as UEs. Note that although terminology from 3GPP LTEnetworks, such as that illustrated in FIG. 1, has been used in thisdisclosure to exemplify the invention, this should not be seen aslimiting the scope of the invention to only the aforementioned system.Other wireless systems, including WCDMA, WMax, UMB and GSM, may alsobenefit from exploiting the ideas covered within this disclosure.

An example network, such as the one shown in FIG. 1, may generallyinclude one or more instances of user equipment (UEs) and one or morebase stations capable of communicating with these UEs, along with anyadditional elements suitable to support communication between UEs orbetween a UE and another communication device (such as a landlinetelephone). Although the illustrated UEs may represent communicationdevices that include any suitable combination of hardware and/orsoftware, these UEs may, in particular embodiments, represent devicessuch as the example UE illustrated in greater detail by FIG. 2.Similarly, although the illustrated base stations may represent networknodes that include any suitable combination of hardware and/or software,these base stations may, in particular embodiments, represent devicessuch as the example base station illustrated in greater detail by FIG.3.

In FIG. 2, the example UE 201 includes a processor 202, a memory 203, atransceiver 204, and an antenna 205. In particular embodiments, some orall of the functionality described as being provided by mobilecommunication devices or other forms of UE may be provided by the UEprocessor 202 executing instructions stored on a computer-readablemedium, such as the memory 203 shown in FIG. 2. Alternative embodimentsof the UE may include additional components beyond those shown in FIG. 4that may be responsible for providing certain aspects of the UE'sfunctionality, including any of the functionality described and/or anyfunctionality necessary to support the solution described.

In FIG. 3, the example base station 301 includes a processor 302, amemory 303, a transceiver 304, and an antenna 305. In particularembodiments, some or all of the functionality described as beingprovided by a mobile base station, a base station controller, a node B,an enhanced node B, and/or any other type of mobile communications nodemay be provided by the base station processor executing instructionsstored on a computer-readable medium, such as the memory 303 shown inFIG. 3. Alternative embodiments of the base station 301 may includeadditional components responsible for providing additionalfunctionality, including any of the functionality identified and/or anyfunctionality necessary to support the solution described.

In general, with respect to LTE, an MBMS UE (User Equipment) does notprovide feedback for link adaptation to the network, i.e., the networkhas to select the modulation and coding scheme, such that the signal canbe decoded by a predefined probability (typically, the 95th percentileis used). Thus, the uplink is only used for unicast transmission.Furthermore, it does not provide any information to the network aboutits MBMS reception status nor about its MBMS reception capabilities. Inthis context, the MBMS reception status differentiates whether the UE isreceiving one or more MBMS services or not receiving any MBMS services.Another status may comprise the UE's interest in receiving one or moreMBMS services. If the UE is interested in or already receiving an MBMSservice, the MBMS reception status may additionally comprise the statuson which frequency or on which frequencies the UE is currently receivingthe MBMS service. Feedback (from the UE to the network) can only beprovided starting from 3GPP Rel-10 during network initiated countingprocedures. For example, if the UE receives a counting request from thenetwork for an MBMS service it is interested to receive, it will respondwith a counting response message.

In principle, in 3GPP Rel-9/10, an MBMS capable UE in idle mode is onlyrequired to receive MBMS on a serving cell, i.e., a cell on which it iscamping, and if the MBMS capable UE is in connected mode it is onlyrequired to receive MBMS in its serving cell.

Depending on UE implementation, MBMS UEs may also be capable ofreceiving MBMS services on so-called non-serving cells. When the UE inidle mode and camping on its serving cell, it can in principle receivethe MBMS from a neighboring cell, which operates on a differentfrequency and broadcasts the MBMS. When the UE is in connected mode, itcould analogously receive the MBMS on a non-serving cell. For example,when the UE is camping on one cell it can in principle receive the MBMSfrom a neighboring cell, which broadcasts the MBMS. Such capabilitiesare primarily determined by the UE's radio front-end and base-banddesign.

In this context the terms serving cell and non-serving cell are used toalso address idle mode UEs, such that no differentiation needs to bedone between idle and connected mode UEs. So for idle mode, non-servingcells are cells on which the UE is not camping and not monitoringpaging, and for connected mode the network has not configured thesenon-serving cells for unicast communication with the UE. Furthermore, anon-serving cell could be provided by the same eNB that provides theserving cell currently configured for the UE, but also by a neighboringeNB within the same network, or even by an eNB broadcasting a differentPLMN (Public Land Mobile Network).

In case a UE wants to receive MBMS from a non-serving cell, the UE mustperform a procedure on the non-serving cell that is similar to theprocedure required for receiving MBMS from the (primary) serving cell.In order to receive MBMS on a serving or non-serving cell, the MBMS UEmust obtain SIB1 (System Information Block 1) to find the schedulinginformation for SIB13 (System Information Block 13), which carriessystem information relevant for MBMS reception. If the MBMS service hasnot started yet, the UE will typically monitor the MBMS specific changenotification for the MCCH (Multicast Control Channel).

In multi-frequency deployments, a specific MBMS will typically only beprovided on one frequency, also referred to as an MBMS frequency. Thenetwork typically applies load balancing between the available neighborcells provided on different frequencies. Thus, the network may decide tomove a UE that is (interested in) receiving an MBMS service to afrequency where the MBMS service of interest is not provided. In orderto support service continuity, the network will use the MBMS statusreport to select an appropriate serving cell for the UE. If the UE isalready receiving an MBMS service on its service cell, it may send aMBMS status report to the network, which will try to keep the UE on thesame frequency as the serving cell. If the UE's serving cell does notprovide the UE's MBMS service of interest, it may send the MBMS statusreport to the network to inform the network on which frequency it isinterested to receive an MBMS. The network will typically configure anappropriate cell operated on that frequency as the UE's new servingcell.

Carrier aggregation (CA) refers to a concept of using multiple carrierson which the UE can transmit and/or receive simultaneously such thathigher data rates can be provided to the terminal. In Rel-10, eachso-called component carrier can be up to 20 MHz wide. Carrieraggregation (CA) functionality was introduced in 3GPP Rel-10 in order toallow for increased data rates by aggregating contiguous ornon-contiguous carriers on the same or different frequency bands forsimultaneous transmission from/to the UE. Thus, higher data rates can beprovided to the UEs, or even more important, operators do not need topossess contiguous spectrum of 20 MHz to reach the advertised LTE (LongTerm Evolution) data rates, but carrier aggregation allows forsimultaneous use of distributed spectrum pieces. In the carrieraggregation context, the serving eNB informs the UE which serving cellsit shall aggregate such that it can tune its radio front-end to thecarrier frequencies used by the serving cells.

In order to be able to configure carrier aggregation or serving cellsaccording to the UE capabilities, 3GPP has defined theSupportedBandCombination Information Element (IE) to inform the networkwhich combination of carriers on which frequency bands the UE supportsfor carrier aggregation.

The SupportedBandCombination IE is, e.g., defined in TS 36.306 V10.2.0,entitled E-UTRA, User Equipment (UE) radio access capabilities (Release10), in Section 4.3.5.2. According to this section, thesupportedBandCombination field defines the carrier aggregation and MIMOcapabilities supported by the UE for configurations with inter-band,intra-band non-contiguous, intra-band contiguous carrier aggregation andwithout carrier aggregation. For each band in a band combination the UEprovides for uplink and downlink the supported CA bandwidth classes andthe corresponding MIMO capabilities. A MIMO capability applies to to allcarriers of a band in a band combination. In all non-CA bandcombinations the UE shall indicate a bandwidth class supporting themaximum channel bandwidth defined for the band.

The serving eNB can derive from the SupportedBandCombination IE, onwhich cells in parallel the UE can support transmission and reception.The cells selected as serving cells for the UE must not exceed theaggregated bandwidth corresponding to the CA bandwidth class providedfor each listed frequency band of a band combination. Configuringserving cells for carrier aggregation means in this context that theserving eNB informs the UE via control signaling which serving cells itshall use. According to 3GPP Rel-10, a carrier aggregation capable UEcan be configured with up to 5 serving cells. The eNB also has to selectthe PCell (Primary serving Cell) and inform the UE about this selection.Thus, the remaining serving cells are automatically SCells (secondaryserving cells). The UE is only required to read system information fromthe PCell, while it does not have to read system information from aSCell. Relevant system information is typically provided to the UE viadedicated signaling in an already configured serving cell.

In 3GPP Rel-10, a minimum requirement for CA and MBMS capable UEs is tobe able to receive MBMS on the PCell (Primary serving Cell), while MBMSreception on other cells than the PCell is up to UE implementation.According to Rel-10 specification, neither the MBMS reception status northe MBMS reception capabilities are known to the network. In thiscontext, MBMS reception capabilities are twofold. First, they comprisethe UE capability on which carriers of a frequency band a UE can receiveat least on MBMS service. Second, they comprise the UE capabilitywhether it can only receive MBMS on a PCell, on any serving cell, or ona non-serving cell.

Up to Rel-10, MBMS UEs cannot report their MBMS reception status to thenetwork such that mobility procedures cannot provide MBMS servicecontinuity. Up to Rel-10, also the MBMS capabilities can not bereported.

Even if a UE informs the network that it is (interested in) receivingMBMS (including the information on which carrier it intends to receiveMBMS), the network still does not know whether or not the UE is capableof receiving unicast traffic on other carriers. If the UE is capable toreceive unicast traffic on other carriers, the network does not know onwhich ones.

In order to allow for MBMS reception, the network—according toRel-10—has to configure the PCell on the carrier on which the UE isinterested to receive MBMS. If the UE indicates interest in multipleMBMS carriers, the network does not make any assumptions.

A Rel-10 network does also not know at which data rate it could scheduleunicast transmission while the UE is receiving an MBMS service withoutexceeding the UEs processing and MIMO (Multiple In Multiple Out)capabilities.

If an MBMS and CA capable UE does not provide its MBMS reception statusat all, the network can not take into account the MBMS reception of theUE for configuring the serving cell(s). If parallel MBMS and unicastreception is ongoing on more carriers than the UE supports, the UE maydrop MBMS or unicast packets depending on its prioritization, resultingin degraded MBMS or unicast performance. Even though lost unicastpackets may be retransmitted, retransmission will reduce the unicastdata rates and degrade user perception on unicast communication.

FIG. 4 depicts a simplified example of a SupportedBandCombination IE asdefined in Rel-10. Each row corresponds with one band combination. TheIE in Rel-10 indicates that the UE is capable of intra-band contiguouscarrier aggregation of up to two carriers with up to 200 resource blocks(class C) in band a (row 1) or band b (row 2). Furthermore, the UE iscapable of inter-band carrier aggregation with one carrier per band withup to 100 resource blocks each (class A).

According to concepts as described herein, a UE supports MBMS receptionon any carrier that could also be configured as a (secondary) servingcell according to a SupportedBandCombination IE which the UE provides tothe network as part of the UE capability signaling. The LTESupportedBandCombination IE is defined in 3GPP TS 36.331, Rel-10 and in3GPP TS 36.306, Rel-10.

One aspect of these concepts is that a network derives from theSupportedBandCombination IE the MBMS reception capabilities of the UEand determines which bearers it may configure as serving cells (PrimaryServing Cells (PCell) or Secondary Serving Cells (SCell)) while stillenabling the UE to receive an MBMS service.

A preferred aspect of these concepts is that, the UE also provides thenetwork with information about the MBMS service(s) or carrier(s) it isinterested in.

With the additional information about the MBMS service(s) or carrier(s)the UE is interested in, the eNB may determines which cells it canconfigure as serving cells while still enabling the UE to receive theMBMS service(s) it is interested in.

In another embodiment, the UE indicates explicitly, e.g., by means of anadditional information element, whether it supports MBMS reception onany carrier that could also be configured as a (secondary) serving cellaccording to the SupportedBandCombination IE. Only if it does, theprocedures as outlined in the first paragraph are applied.

Note that reusing the SupportedBandCombination IE requires aligning theband combinations supported for carrier aggregation and for MBMS. Inother words, a UE that offers unicast and MBMS reception on a certainband combination must also support carrier aggregation in thatcombination. However, this seems to be an acceptable restriction.

In general the disclosure relates to methods in a mobile communicationsystem comprising a network node such as a base station (e.g., an eNB oran RNC) and a UE.

According to one embodiment a method in a network node (e.g., an eNB oran RNC) is provided. The method may comprise steps as already indicatedabove.

The method in a network node may comprise the receiving an indication(such as a flag) from a User Equipment (such as a terminal) whether theUser Equipment supports MBMS reception on at least one SCell and/or onat least one non-serving cell.

The method in a network node may further comprise the receiving aninformation element (e.g., a SupportedBandCombination IE) comprisinginformation of a band combination supported by the UE for carrieraggregation.

The method in a network node may further comprise configuring at leastone carrier as serving cell based on the received indication and thereceived information element.

Within the method in a network node, the configuration of at least onecarrier may further be based on an indication whether the UE isinterested in receiving MBMS.

According to one embodiment a method in a UE is provided. The method maycomprise the steps as already indicated above.

The method in a UE may comprise transmitting an indication (such as aflag) to a network node whether the UE supports MBMS reception on atleast one SCell and/or on at least one non-serving cell. The method in aUE may further comprise transmitting whether the UE is interested inreceiving MBMS.

According to one aspect of the disclosure, a base station is provided,which is adapted to perform the above method in a base station.According to one aspect of the disclosure a UE is provided, which isadapted to perform the above method in a UE.

FIG. 5 shows an example scenario, in which two frequency bands a and bare considered. The frequency band a comprises a carrier f1 and acarrier f2, the frequency band b comprises a carrier f3 and a carrierf4. MBMS is provided on carrier f2 only, i.e., MBMS is not provided oncarrier f1, f3 and f4.

With respect to this multi-frequency scenario (with carriers f1, f2, f3and f4, where MBMS is provided on carrier f2 in band a) the followingexamples describe how the SupportedBandCombination IE with theadditional flag indicating whether the UE is capable of receiving MBMSon other cells than the PCell can be used to assist the network to makesuitable (primary/secondary) serving cell configurations. As describedabove, the flag can be explicit or implicit.

In these examples, an MBMS and CA capable UE with the supported bandcombinations summarized in FIG. 1 is considered.

Furthermore, it is assumed, that this UE indicates support for receivingMBMS on cells/carriers other than the PCell and that it informs thenetwork about its intention to receive MBMS on a certain carrier. Withthis information at hand the eNB can determine whether the currentlyconfigured serving cell(s) allow the UE to receive MBMS as intended andif not, which reconfiguration could be performed. Several examples/casesfor such a UE are described in the following.

Case 1: If the UE has its PCell on f2, no SCells configured and itindicates interest in the MBMS service offered on this carrier, the eNBknows that the UE will be able to receive MBMS. Since no unicast data isscheduled to this UE in MBSFN subframes, no special care needs to betaken of the UE's processing capabilities. This applies already forRel-10 UEs.

Case 2: We assume that the UE has its PCell on f1, f3 or f4 and noSCells configured. If the UE indicates interest in an MBMS service onf2, the network may trigger a PCell handover to f2 to ensure that the UEcan receive the MBMS service as intended. However, the informationprovided by the UE in combination with the fact that no SCells areconfigured, allows the network to maintain the currently configuredPCell and be sure that the UE's RF capabilities still allow forreceiving MBMS on f2. If the UE has its PCell on f1, this can be derivedfrom the intra-band aggregation capability signaled in row 1 (see FIG.1). If the UE has its PCell on f3 or f4 it is concluded from theinter-band aggregation support signaled in row 3 that the UE can receiveMBMS on f2, which is a non-serving cell.

Case 3: If the UE is configured for intra-band carrier aggregation onband a (carriers f1+f2), the UE is also capable of receiving MBMS on f2no matter whether this is the PCell or the SCell.

Case 4: If the UE is configured for intra-band carrier aggregation onband b (carriers f3+f4), see row 2 (FIG. 1), the network knows that theUE is not able to receive MBMS on f2. As soon as the UE indicatesinterest in receiving MBMS on carrier f2, the network should thereforeat least release one of the serving cells on band b. It may optionallyconfigure a serving cell on f2 in combination with either f3 or f4, seerow 3, or it could setup carrier aggregation of f1 and f2, see row 1.

If the network is not forced to configure the MBMS carrier/cell as thePCell to ensure service continuity for the UE, the network has the majoradvantage that it can flexibly select the PCell in carrier aggregationscenarios based on both the channel quality on the carriers and the bandcombination capabilities indicated by the UE. Thus, the network maymaximize or maintain transmission and reception performance for unicastwhile MBMS reception is ongoing.

FIG. 6 schematically illustrates a flowchart of a method in a wirelessnetwork according to one embodiment. In a step S601, an eNodeB receivesa band combination information element. In a step S602, the eNodeBreceives a flag whether the UE can receive MBMS on a secondary cell ornon-serving cell. The flag can be implicit or explicit. If ‘yes,’ aserving cell is configures according to concepts as, e.g., described in3GPP Rel-10. If ‘no’, it is checked in a step S603, whether the UE isinterested in MBMS reception. If yes′, it is checked, in a step S604,whether the UE is capable of receiving MBMS on a secondary ornon-serving cell.

If ‘no’, the MBMS cell is configured as primary serving cell, step S605.If yes′, in a step S606, at least one band combination is selected onwhich the MBMS cell is covered. Depending on the eNB strategy, the UEwill choose an appropriate band combination among the selected bandcombinations, e.g., based on the signal qualities for the UE or the loadon these carriers.

In a step S607, it is checked whether carrier aggregation is configuredfor the UE. If ‘no,’ in a step S608, a serving cell is selectedaccording to any band combination. The eNB may select a specific bandcombination at a later point of time when the UE is configured forcarrier aggregation and the eNB configures more serving cells for the UEaccording to step S609.

If ‘yes’ the primary serving cell is chosen according to the at leastone selected band combination, step S609. In a step S610, at least onesecondary serving cell is chosen according to the at least one selectedband combination.

In this way, continuity of an MBMS service is achieved, while offeringflexibility in selecting serving cells according to certain measures,such as quality of MBMS or unicast service.

FIG. 7 schematically illustrates a flowchart of a method for supportingcontinuity of a Multimedia Broadcast Multicast Service, MBMS, for aterminal. To implement the method, one or more of the steps illustratedin FIG. 7 may be performed by a network e.g., a radio access networksuch as an E-UTRAN. In particular, the one or more of the stepsillustrated in FIG. 7 may be performed in a base station such as aneNodeB of a mobile communication network.

In a step S701, the base station receives, from the terminal, aninformation element informing the base station of a combination ofbands, which the terminal supports for carrier aggregation,

The information element may be the Supported BandCombination InformationElement as e.g., defined in the Rel-10 LTE standards. The informationelement may comprise a combination of frequency bands, wherein each bandis associated with a bandwidth class supported for carrier aggregation.The term informing the base station may comprises that the informationelement actually comprises the particular information or that the basestation determines the particular information from that informationelement possibly in combination with other resources of informationavailable at the base station.

From the received information element, the base station can derivecarriers that can be configured as a serving cell for the terminal. Theserving cell can e.g., be a primary serving cell and/or at least onesecondary serving cell. The terminal supports MBMS reception on anycarrier configurable as a serving cell for the terminal according to theinformation element. In this way the information on which carrier theterminal is capable to receive MBMS can implicitly be signaled to thebase station.

In a step S703, the base station derives, from the received informationelement, MBMS reception capabilities of the terminal. The capabilitiescomprise the carriers on which the terminal can receive MBMS. Thecapabilities may further comprise whether the MBMS carrier must beconfigured as PCell, SCell or any non-serving cell covered by at leastone of the supported band combinations.

In a step S704, the base station determines a number of carriers, whichthe base station can configure as a serving cell of the terminal, suchthat the terminal is enabled to receive at least one MBMS. Thedetermination is based on the derived MBMS capabilities. The servingcell can be a primary serving cell or at least one secondary servingcell.

The base station may configure at least one carrier as serving cell ofthe terminal on the basis of the determined number of carriers. The basestation can configure the at least one carrier as serving cell of theterminal, such that the terminal is enabled to receive the at least oneMBMS from a non-serving cell of from a serving cell.

For a terminal in connected mode, a serving cell is a cell on which theterminal can send and receive unicast data, i.e., where a radio beareris established. A non-serving cell broadcasts all information that isneeded for a terminal to connect to it. No radio bearers are establishedin a non-serving cell.

In an optional further step S705, the base station obtains, from theterminal, an indication of at least one MBMS and/or at least one carrierof an MBMS, in which the terminal is interested. For example, theterminal sends a frequency of a MBMS service to the base station, toindicate that the terminal is interested in receiving a broadcastservice (MBMS) on this frequency.

In an optional further step S706, the base station configures at leastone carrier as serving cell of the terminal on the basis of thedetermined number of carriers and the received indication, such that theterminal is enabled to receive the at least one MBMS service theterminal is interested in. For example, the base station configures theserving cell on the basis of the at least one determined carrier that iscovered by the at least one supported band combination and on the basisof the MBMS service for which the terminal has indicated interest. Aterminal is enabled to receive an MBMS service when it can receive theMBMS from either a serving or a non-serving cell.

In an optional step S702, the base station obtains, from the terminal,an explicit indication that the terminal supports MBMS reception on anycarrier that is configurable as a serving cell according to theinformation element. The explicit indication may be given via anadditional or a second information element. For example, only if theadditional or second information element indicates support of MBMSreception on any carrier configurable as serving cell according to theinformation element the outlined procedure shall be performed. Forexample, only if respective MBMS support is indicated by the additionalor second information element, the deriving step S703, the determiningstep S704 and possibly further steps such as steps S705 and/or S706 areperformed.

FIG. 8 schematically illustrates a flowchart of a method in a terminalfor supporting continuity of a MBMS service for the terminal. Conceptsof the invention are described from a base station perspective withrespect to FIG. 7, whereas similar concepts are described from aterminal perspective with respect to FIG. 8. Continuity of a MBMSservice comprises that the continuity of a MBMS service is supportedwhen a service cell is configured on a particular frequency. Inparticular, MBMS reception can be ensured on this serving cell or on anon-serving cell where the serving and non-serving cells are covered bya supported band combination.

In a step S801, the terminal sends to a base station, an informationelement informing the base station of a combination of bands, which theterminal supports for carrier aggregation. From the information elementcarrier can be derived by a base station, which can be configured as aserving cell. The terminal supports MBMS reception on any carrierconfigurable as a serving cell for the terminal according to theinformation element. In this way the information on which carriers theterminal is capable to receive MBMS can implicitly be signaled to thebase station. The information element may be theSupportedBandCombination Information Element as e.g., defined in theRel-10 LTE standards. The information element is further discussed withrespect to FIG. 7.

In an optional step S802, the terminal indicating to the base station atleast one MBMS and/or at least one carrier of an MBMS, in which theterminal is interested. The terminal may receive the at least one MBMSfrom a non-serving cell or from a serving cell.

In an optional step S803, the terminal indicates explicitly to the basestation that the terminal supports MBMS reception on any carrier that isconfigurable as a serving cell according to the information element. Theexplicit indication may be done via an additional or a secondinformation element.

FIG. 9 schematically illustrates exemplary structures for implementingthe above concepts in a base station 901 according to one embodiment. Inthe illustrated structure, the base station 901 includes a radiointerface 902 for data transmission to or from the terminal 1001. It isto be understood that for implementing transmitter (TX) functionalitiesthe radio interface 902 may include one or more transmitters 904, andthat for implementing receiver (RX) functionalities the radio interface130 may include one or more receivers 132. The receiver 903 may inparticular be configures to receive, from the terminal, the abovementioned information element. Further, the base station 901 may includean interface 905 for communicating with other nodes of the network.

Further, the base station 901 includes a processor 906 coupled to theinterfaces 902 and 905 and a memory 907 coupled to the processor 906.The memory 160 may include a Read Only Memory (ROM), e.g., a flash ROM,a Random Access Memory (RAM), e.g., a Dynamic RAM (DRAM) or Static RAM(SRAM), a mass storage, e.g., a hard disk or solid state disk, or thelike. The memory 907 includes suitably configured program code to beexecuted by the processor 906 so as to implement the above-describedfunctionalities of the BS 900. More specifically, the memory 907 mayinclude a control module 908 for accomplishing the above-describedconcepts such as deriving, from the received information element, MBMSreception capabilities of the terminal, and for determining number ofcarriers. Further, the memory 907 may include a configuration module 909for accomplishing the above described concepts such as configuring atleast one carrier as serving cell of the terminal.

It is to be understood that the structure as illustrated in FIG. 9 ismerely schematic and that the base station 901 may actually includefurther components which, for the sake of clarity, have not beenillustrated, e.g., further interfaces or additional processors. Also, itis to be understood that the memory 907 may include further types ofprogram code modules, which have not been illustrated. For example, thememory 907 may include program code modules for implementing typicalfunctionalities of a base station, e.g., known functionalities of aneNodeB.

According to some embodiments, also a computer program product may beprovided for implementing concepts according to embodiments of theinvention, e.g., a computer readable medium storing the program codeand/or other data to be stored in the memory 907.

FIG. 10 schematically illustrates exemplary structures for implementingthe above-described concepts in a terminal 1001. In the illustratedstructure, the terminal 1001 includes a radio interface 1002 forperforming data transmission to or from a mobile network, e.g., via thebase station 901. In particular, the radio interface 1002 may beconfigured for sending the above described information element to thebase station 901. It is to be understood that for implementingtransmitter (TX) functionalities the radio interface 1002 includes oneor more transmitters 1003 and that for implementing receiver (RX)functionalities the radio interface 1002 may include one or morereceivers 1004.

Further, the terminal 1001 includes a processor 1005 coupled to theradio interface 1002 and a memory 1006 coupled to the processor 1005.The memory 1006 may include a ROM, e.g., a flash ROM, a RAM, e.g., aDRAM or SRAM, a mass storage, e.g., a hard disk or solid state disk, orthe like. The memory 1006 includes suitably configured program code tobe executed by the processor 1005 so as to implement the above-describedfunctionalities of the terminal 1001. More specifically, the memory 1006may include a configuration module which e.g., configures theinformation element such that the terminal supporting MBMS reception forany carrier configurable as a serving cell for the terminal according tothe information element. Further, the memory 1006 may include a controlmodule 380 for performing various control operations,

It is to be understood that the structure as illustrated in FIG. 9 ismerely schematic and that the terminal 1001 may actually include furthercomponents which, for the sake of clarity, have not been illustrated,e.g., further interfaces or additional processors. Also, it is to beunderstood that the memory 1006 may include further types of programcode modules, which have not been illustrated. For example, the memory1006 may include program code modules for implementing typicalfunctionalities of a terminal or program code of one or moreapplications to be executed by the processor 1005.

According to some embodiments, also a computer program product may beprovided for implementing concepts according to embodiments of theinvention, e.g., a computer-readable medium storing the program codeand/or other data to be stored in the memory 1006.

The embodiments as described above support the continuity of MBMS by theconcept that the terminal implicitly informs the base station of theMBMS reception capabilities of the terminal and the base station usesthis information to determine a number of carriers for configuring aserving cell such that MBMS reception can be enabled. This also offers afurther degree of freedom in configuring a serving cell. For example,the serving cell can be configured such that an improved quality ofunicast and or MBMS transmission is obtained, e.g., a reduced number oflost packets in the respective service is obtained. The further degreeof freedom can also be used to reduce certain types of interference.Still the continuity of MBMS is supported. The MBMS reception may beperformed on one of the configured serving cells or on a non-servingcell.

According to the concepts described above, the network (or base station)can ensure that the UE (or terminal) is able to receive MBMS services asdesired while still being able to configure (primary/secondary) servingcells for unicast communication with a large degree of flexibility.

Suitable unicast configuration of serving cells avoids that the UE (orterminal) has to drop MBMS or unicast packets. If the UE (or terminal)supports MBMS reception on other cells than the PCell, the PCell can beoptimally selected by the network to maximize the performance forunicast.

The use of an additional information element indicating whether or notthe UE (or terminal) supports MBMS reception on any carrier that couldalso be configured as a (secondary) serving cell according to theSupportedBandCombination IE allows to introduce the feature in abackwards compatible way. That means, only for UEs (or terminals)supporting this feature the network derives the MBMS receptioncapabilities from the SupportedBandCombination IE.

It is to be understood that the examples and embodiments as explainedabove are merely illustrative and susceptible to various modifications.For example, the concepts could be used in types of mobile network whichdiffer from the above-mentioned examples of an LTE mobile network.Further, it is to be understood that the above concepts may beimplemented by using correspondingly designed software in existingmobile network nodes or UEs, or by using dedicated hardware of suchmobile network nodes or UEs.

The present invention may, of course, be carried out in other specificways than those herein set forth without departing from the spirit andessential characteristics of the invention. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

1. A method implemented in a base station of a mobile communicationnetwork for supporting a Multimedia Broadcast Multicast Service, MBMS,for a terminal, the method comprising: receiving, at the base stationfrom the terminal, an indication of a combination of bands that theterminal supports for carrier aggregation; deriving, based on theindication, MBMS reception capabilities of the terminal; andconfiguring, based on the derived MBMS reception capabilities of theterminal, at least one carrier for the terminal, such that the terminalis enabled to receive at least one MBMS.
 2. The method of claim 1wherein deriving, from the received indication, MBMS receptioncapabilities of the terminal comprises determining that the terminalsupports MBMS reception on any carrier configurable as a serving cellfor the terminal.
 3. The method of claim 2 wherein deriving, from thereceived indication, MBMS reception capabilities of the terminalcomprises determining the terminal supports MBMS reception on anycarrier configurable as a secondary serving cell for the terminal. 4.The method of claim 1 further comprising obtaining, from the terminal,an indication of at least one of an MBMS and a carrier of an MBMS, inwhich the terminal is interested.
 5. The method of claim 4 whereinconfiguring at least one carrier for the terminal is further based onthe indication from the terminal of at least one MBMS and a carrier ofan MBMS.
 6. The method of claim 1 wherein configuring at least onecarrier for the terminal comprises configuring a carrier such that theterminal is enabled to receive the at least one MBMS from a non-servingcell.
 7. The method of claim 1 wherein configuring at least one carrierfor the terminal comprises configuring a carrier such that the terminalis enabled to receive the at least one MBMS from a serving cell.
 8. Themethod of claim 1 wherein the indication is a Long Term Evolution, LTE,SupportedBandCombination IE.
 9. The method of claim 1 further comprisingobtaining, from the terminal, an explicit indication that the terminalsupports MBMS reception on any carrier that is configurable as a servingcell according to the indication.
 10. A method implemented in a terminalfor supporting a Multimedia Broadcast Multicast Service, MBMS, for theterminal, the method comprising: configuring, by the terminal, anindication from which a base station is enabled to derive MBMS receptioncapabilities of the terminal; sending the indication to the base stationto inform the base station of a combination of bands that are supportedby the terminal for carrier aggregation, wherein the terminal supportsMBMS reception for any carrier configurable as a serving cell for theterminal according to the combination of bands in the indication; andreceiving at least one MBMS on a carrier configured by the base stationbased on the MBMS reception capabilities of the terminal.
 11. The methodof claim 10 further comprising indicating to the base station at leastone of an MBMS and a carrier of an MBMS, in which the terminal isinterested.
 12. The method of claim 10 further comprising receiving theat least one MBMS from a non-serving cell.
 13. The method of claim 10further comprising receiving the at least one MBMS from a serving cell.14. The method of claim 10 wherein the indication is a Long TermEvolution, LTE, SupportedBandCombination IE.
 15. The method of claim 11further comprising indicating to the base station that the terminalsupports MBMS reception on any carrier that is configurable as a servingcell according to the indication.
 16. The method of claim 16 furthercomprising indicating to the base station that the terminal supportsMBMS reception on any carrier configurable as a secondary serving cellfor the terminal.
 17. A base station for a mobile communication networkand for supporting a Multimedia Broadcast Multicast Service, MBMS, for aterminal, the base station comprising: a receiver configured to receive,from the terminal, an indication of a combination of bands that theterminal supports for carrier aggregation; a processing circuitconfigured to: derive, from the received indication, MBMS receptioncapabilities of the terminal; and configure, based on the derived MBMSreception capabilities of the terminal, at least one carrier for theterminal, such that the terminal is enabled to receive at least oneMBMS.
 18. The base station of claim 17 wherein the terminal supportsMBMS reception on any carrier configurable as a serving cell for theterminal.
 19. The base station of claim 18 wherein the terminal supportsMBMS reception on any carrier configurable as a secondary serving cellfor the terminal.
 20. The base station of claim 1 wherein the processingcircuit is further configured to obtain, from the terminal, anindication of at least one of an MBMS and a carrier of an MBMS, in whichthe terminal is interested.
 21. The base station of claim 20 whereinconfiguring, by the processing circuit, at least one carrier for theterminal is further based on the indication from the terminal of atleast one MBMS and a carrier of an MBMS
 22. The base station of claim 17wherein configuring, by the processing circuit, at least one carrier forthe terminal comprises configuring a carrier, such that the terminal isenabled to receive the at least one MBMS from a non-serving cell. 23.The base station of claim 17 wherein configuring, by the processingcircuit, at least one carrier for the terminal comprises configuring acarrier, such that the terminal is enabled to receive the at least oneMBMS from a serving cell.
 24. The base station of claim 17 wherein theprocessing circuit is further configured to obtain, from the terminal,an indication that the terminal supports MBMS reception on any carrierthat is configurable as a serving cell according to the indication. 25.A terminal for a wireless communication network and for supporting aMultimedia Broadcast Multicast Service, MBMS, for the terminal, theterminal comprising: a processing circuit configured to configure anindication from which a base station is enabled to derive MBMS receptioncapabilities of the terminal; a transmitter configured to send theindication to the base station to inform the base station of acombination of bands that are supported by the terminal for carrieraggregation, wherein the terminal supports MBMS reception for anycarrier configurable as a serving cell for the terminal according to thecombination of bands in the indication; and a receiver configured toreceive at least one MBMS on a carrier configured by the base stationbased on the MBNMS reception capabilities of the terminal.
 26. Theterminal of claim 25 wherein the processing circuit is furtherconfigured to indicate to the base station at least one of an MBMS and acarrier of an MBMS, in which the terminal is interested.
 27. Theterminal of claim 25 further comprising a receiver configured to receivethe at least one MBMS from a non-serving cell.
 28. The terminal of claim25 further comprising a receiver configured to receive the at least oneMBMS from a serving cell.
 29. The terminal of claim 25 wherein theprocessing circuit is further configured to indicate to the base stationthat the terminal supports MBMS reception on any carrier that isconfigurable as a serving cell according to the indication.
 30. Theterminal of claim 25 wherein the processing circuit is furtherconfigured to indicate to the base station that the terminal supportsMBMS reception on any carrier configurable as a secondary serving cellfor the terminal.